Similar Problem
My version is 1.5.2 but I have frame rate issues too. Not while playing but on the menu screen. When I choose create fast mission I can't select any options or even close the menu. Only way for me to play is instant action.
System Specs: intel i7 3610QM @2.3 Ghz, 8mb ram, Geforce GTX 660m w/2GB gddr overclocked with msi afterburner
I know I'm on a lappy, but it used to work fine until an update around December. I've tried dropping the settings to low, disabling v-sync, etc. with no improvement whatsoever.
